Mercedes C250 CDi Coupé (204 bhp) Intermittent lack of power

JUS

I searched today for 'Mercedes C350 CSI remap' and came across a very knowledgeable M-B forum...was at work so don't have the address but might be worth googling that and asking the question on that forum. There was a loss of power sticky thread in the engine section from memory [emoji4]

DVD-Man

Do you have another Merc dealer nearby?  A call to them might help if a tech has seen the issue there.

mikes48

I'm stuck with the current dealer really - but they are an M-B main dealer, so I'm OK with that - because the fault came up shortly before the warranty expired, so they're continuing under the warranty.

They referred it back to M-B UK yesterday, and have today been advised to change the ECU. They are just awaiting an order number from M-B to get the ECU on a loan basis, which makes me think that neither the dealer nor M-B are entirely confident with the diagnosis

FZR400RRSP

I hate the way it's always 'assumed' it's an electronic fault these days.
As car-man has said, it could be a good old fashioned mechanical fault like a sticky EGR valve.
Changing the ECU seems a tad OTT when it could be a far cheaper part.

adamduk

A totally leftfield suggestion, but could be something like water or condensation in a connection somewhere, especially in the underbonnet electrical centre (below the fuses/relays)

mikes48

Update - the car's been with the M-B main dealer for virtually a month now.

Last word was that they have got M-B Germany to agree to supplying an ECU on a sale or return basis, to see if that fixes the problem. Sounds to me like neither of them have much confidence in their "diagnosis".

So the new ECU was supposed to be despatched from Germany last Thursday, to arrive in Preston on Saturday, be fitted either on Saturday (fairly quick swap, I believe), road test today/tomorrow, and Bob's your uncle.

We'll see tomorrow (Tues 24 Nov).

At least the dealer has confirmed that the issue is covered by the warranty, the fault having been reported a few days before the warranty expired.

So my Christmas present to my wife this year, if we ever get her car back, will be a further year's warranty, at the (not unreasonable) price of just over £500. Without that assurance, I'm afraid we just won't trust the car, long-term, certainly not for continental holidays - and my XF's getting a bit long in the tooth, so the Merc may well have to go. Shame, nice car when it works, and my wife loves it.

PS - for the benefit of @eob , when my Mum first saw the car she burst into Janis Joplin's song. My Mum's 90 btw God bless her .

kps

Hi Mikes48,

I am experiencing the same problem with my C-Class. Were you ever able to get it fixed your's?

Thanks

mikes48

Never did get it fixed, and we didn't buy the extended warranty either, reason being that because the car was in the main dealer workshop, being "repaired", M-B would only sell us the extended warranty at a higher price (about 50% higher iirc) and there would be a 6 week deferment of the policy start. You couldn't make it up!

What really p'eed me off was that the main dealer couldn't accurately diagnose the fault. So we traded it in for a CLS - which seems more reliable, although it is the same engine as the C. Saying that, we've bought extended warranties twice for the CLS.

Shame when you buy a Mercedes and only feel comfortable when you pay £500  a year to extend the warranty. You could put the same amount aside of course, and if you're lucky the car will be OK and you're quids in. OTOH, what could a M-B repair bill be .

So good luck with yours - hope it gets sorted at a reasonable price

Andrew40

Same to me 3 years now ,any one fixed this issue ,but after restart the engine all fine for a while

Andrew40

Guys ,i solved that problem ,check vacuum reservoir piping ,mine is been mixed up ,swaped it over and problem disapared ,could be leakege problem as well.nobody could find a problem ,for 3 years.